Untitled

Abstract

In this work, we characterized chemically the N-acetyl-D-galactosamine specific lectin from Amaranthus leucocarpus syn hypocondriacus lectin (ALL). It is a dimeric glycoprotein composed by three isoforms with pl at 4.8, 4.9, and 5.2. Circular dichroism analysis indicated that the secondary structure of ALL contains 45% of \bibeta-sheet and 5% of \bialpha-helix. Amino acid sequence of the purified lectin and its isoforms was determined from peptides obtained after trypsin digestion by MALDI-TOF (Matrix assisted laser desorption ionization-time of flight). The tryptic peptides prepared from the purified lectin and the three isoforms showed different degrees (80 to 83%) of identity with the amino acid sequence belonging to a previously described high nutritional value protein from A. hypocondriacus not shown at the time to be a lectin. Furthermore, analysis of tryptic peptides obtained from ALL previously treated with peptide N-glycosidase, revealed a 93% identity with the aforementioned protein. Presence of N-glycosidically linked glycans of the oligomannosidic type and, in minor proportion, of the N-acetyllactosaminic type glycans was determined by affinity chromatography on immobilized Con A.

Amaranthin-Like Proteins with Aerolysin Domains in Plants

“…Currently, the lectin activity of amaranthin domains has only been investigated for lectins purified from the Amaranthus species ( A. caudatus, Amaranthus leucocarpus, Amaranthus hypochondriacus ). These amaranthin domains specifically interact with T-antigen and N -acetylgalactosamine ( Ozeki et al, 1996 ; Transue et al, 1997 ; Hernández et al, 2001 ). Considering the significant sequence differences between all identified amaranthin domain sequences, it is likely that the carbohydrate-binding specificities for some of these amaranthin domains might be altered or could even be lost as a result of sequence variation and altered protein folding.…”

Amaranthus leucocarpus lectin recognizes a moesin‐like O‐glycoprotein and costimulates murine CD3‐activated CD4+ T cells

“…This lectin has been isolated from A . leucocarpus seeds 9, and its hemagglutination activity is specifically inhibited by GalNAc 8–10. ALL binds murine thymocytes and thymic dendritic cells, peritoneal macrophages, and peripheral blood T cells, but not B cells 11–13.…”